1. Field of the Invention
The present invention relates to regenerative heaters and, in particular, to blast furnace stoves.
2. Description of the Prior Art
It is known that certain efficiencies may be obtained in the use of blast furnaces when the blast of air provided to such furnaces is preheated to a temperature in the approximate range of 1500.degree. to 2450.degree. F. The preheating of this air is conventionally accomplished in a refractory lined stove which is positioned adjacent to the blast furnace to which it provides the hot blast. These stoves are generally equipped with an interior, vertical wall which partitions the stove into a combustion chamber and a checker chamber containing checkerbrick. Hot gases formed in the combustion chamber flow upwardly over the wall and then downwardly through the checker chamber. After the checkerbricks have been sufficiently heated, the direction of the gas flow is reversed and air is passed first upwardly over the checkerbrick and then downwardly through the combustion chamber so as to preheat the air before it is discharged to the blast furnace.
The partitioning wall often consists of multiple layers of brick. Facing the combustion chamber is a layer of brick commonly known as the skin wall, and facing the checker chamber there is another layer of refractory brick which is commonly known as the breast wall. Interposed between the skin wall and the breast wall, a layer of insulating material is also often provided.
The above described operation of the stove may result in a condition where the temperature in the lower part of the combustion chamber exceeds 2500.degree. F., while the temperature in the lower part of the checker chamber is only about 600 .degree. F. Under such conditions there is a significant temperature differential across the partitioning wall, and this temperature differential may result in a corresponding differential of expansion between bricks on opposite sides of the partitioning wall. Ordinarily, the expansion of bricks in the skin wall will be greater than that of the material in the intermediate insulating layer which will, itself, exceed that of bricks in the breast wall. This expansion differential will be likely to result in the partitioning wall being concavely deformed and in a radial movement of its bricks toward the checker chamber. As a consequence of this radial movement, the refractory bricks in the skin wall will tend to press the intermediate, insulating layer against the refractory bricks in the breast wall. Because the insulating layer is generally softer than the refractory bricks in the skin and breast wall, the insulating layer will tend to be crushed or otherwise damaged as a result of the above described movement in the partitioning wall. Additionally, it is also found that certain materials which may have particularly good insulating properties may also tend to sag or be vertically compressed by their own weight at the temperatures which occur inside a blast furnace stove. It is, therefore, the object of the present invention to provide a means for protecting the insulating layer of the partitioning wall from such damage and deterioration.